Focal Adhesion Kinase (FAK herein) is a non-receptor protein tyrosine kinase that has both signaling and scaffolding functions in focal adhesions. FAK is a central regulator of cell adhesion, migration, and survival. As such, FAK inhibition provides an important avenue for treating a number of cancers. In treatment, it is important to identify patients who will respond to FAK inhibitors from those who will not, so that non-responders can be provided alternative treatment.